Frequency and Role of HPV in the Progression of Epithelial Dysplasia to Oral Cancer

Human papillomavirus DNA (HPV DNA) and p16 and p53 protein expressions were investigated for their role in transforming dysplasia into squamous cell carcinoma of the oral cavity in a non-smoker and non-drinker patient group. A total of 56 oral biopsies from non-smoker and non-drinker patients were analyzed. The specimens were grouped into three categories: group 1 included 31 cases of hyperplastic mucosa and mild dysplasia, group 2 included 14 cases of moderate and severe dysplasia, while group 3 comprised 11 cases of invasive squamous cell carcinomas. In all cases, immunohistochemical methods were performed to detect p16 and p53 protein expressions. The nested polymerase chain reaction for HPV (nested HPV-PCR) and the catalyzed signal-amplified colorimetric DNA in situ hybridization (CSAC-ISH) methods were applied for HPV DNA detection and typing of high-risk genotype. P16 protein, absent from all specimens of group 1, was especially noted in group 2 (92.86%) and in group3 (54.55%). Five out of 14 of group 2 cases (35.71%) and 3/11 (27.27%) of group 3 were HPV DNA positive. The HPVs detected were of both high-risk and low-risk genotype. The analysis of the relationship between HPV and p16 protein expression revealed that all the group 2 and 3 samples with HPV DNA, overexpressed p16 protein. The results suggest that HPV could be a molecular marker in group 2 and 3 specimens in non-smoker and non-drinker patients. The virus may play an etiological role in carcinogenesis in the oral cavity. The association between HPV and p16 overexpression suggests a molecular mechanism similar to that found in cervical cancer.